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Lecture 19: Cellular Respiration.
By the end of this lecture you should be
able to…
Describe respiration as a redox reaction.
Concepts and terms: reductant, oxidant,
NADH
Describe the structure of mitochondria
Discuss the major components of cellular
respiration.
Concepts and terms: glycolysis, Krebs
cycle, electron transport
Describe the major inputs and products of
each component of the respiratory
pathway.
Describe chemiosmosis.
Concepts and terms: ATP synthase,
proton gradient.
Contrast aerobic and anaerobic respiration.
Concepts and terms: fermentation,
lactic acid
Describe the role of inhibitors in studying
respiratory biochemistry.
Assigned reading: Chapter 9 in the text.
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http://cellbio.utmb.edu/cellbio/mitochondria_1.htm#powerhouses
Mitochondria are the cells' power sources.
Usually they are rod-shaped; however they can be round.
Cellular respiration:
C6H12O6 + 6O2
6CO2 + 6 H2O
NAD: nicotinamide adenine dinucleotide
• Electrons from food are transferred initially to NAD+
• Some of the energy released from NADH is used to make ATP
http://ntri.tamuk.edu/cell/mitochondrion/glycpics.html
Substrate-level phosphorylation
Oxidative phosphorylation
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Figure 9.11 A closer look at the Krebs cycle (Layer 1)
Figure 9.11 A closer look at the Krebs cycle (Layer 2)
Figure 9.11 A closer look at the Krebs cycle (Layer 3)
Figure 9.11 A closer look at the Krebs cycle (Layer 4)
• The conversion of
pyruvate and the
Krebs cycle
produces large
quantities of
electron carriers.
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Peter Mitchell (1920 - 1992) Nobel
Laureate…
…1961 paper introducing the
chemiosmotic hypothesis.
http://www.life.uiuc.edu/crofts/bioph354/lect11.html
Chemiosmosis
Proton-motive force
Oxidative phosphorylation
• A protein complex,
ATP synthase, in the
cristae actually makes
ATP from ADP and Pi.
• ATP used the energy of
an existing proton
gradient to power ATP
synthesis.
– This proton gradient
develops between the
intermembrane space
and the matrix.
Fig. 9.14
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
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Aerobic
Anaerobic
During extreme exertion…
Initially, stored ATP is
metabolized (~5mmol/kg
muscle. It’s gone in about 5 s.
Then phosphocreatine is
converted to ATP; gone in
another 5 s.
Then glycolosis starts
(anaerobic respiration)…oops,
lactate accumulates.
Anaerobic respiration kicks in
after about 2 min.
Feedback mechanisms control
cellular respiration